Novel CNT Supported Molybdenum Catalyst for Detection of L-Cysteine in Its Natural Environment

In this study, novel carbon nanotube-supported Mo (Mo/CNT) catalysts were prepared with the sodium borohydride reduction method for the detection of L-cysteine (L-Cys, L-C). Mo/CNT catalysts were characterized with scanning electron microscopy with elemental dispersion X-ray (EDX-SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectrometry (UV-vis), temperature-programmed reduction (TPR), temperature programmed oxidation (TPO), and temperature-programmed desorption (TPD) techniques. The results of these advanced surface characterization techniques revealed that the catalysts were prepared successfully. Electrochemical measurements were employed to construct a voltammetric L-C sensor based on Mo/CNT catalyst by voltammetric techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Further measurements were carried out with electrochemical impedance spectroscopy (EIS). Mo/CNT/GCE exhibited excellent performance for L-C detection with a linear response in the range of 0–150 µM, with a current sensitivity of 200 mA/μM cm2 (0.0142 μA/μM), the lowest detection limit of 0.25 μM, and signal-to-noise ratio (S/N = 3). Interference studies showed that the Mo/CNT/GCE electrode was not affected by D-glucose, uric acid, L-tyrosine, and L-trytophane, commonly interfering organic structures. Natural sample analysis was also accomplished with acetyl L-C. Mo/CNT catalyst is a promising material as a sensor for L-C detection

Determination of the dispersion of supported Pt particles by gas-phase and liquid-phase measurements

The dispersion of a Pt/gamma-Al2O3 catalyst was investigated by various experimental techniques. The values obtained by gas-phase hydrogen and carbon monoxide adsorption and transmission electron microscopy (TEM) were consistent for the metal:adsorbate stoichiometry of 1:1. However, these methods overestimated the number of active sites available for a liquid-phase reaction. For the hydrogenation of styrene in the presence Of CS2 as a catalyst poison, only the defect sites were found to be active in the catalytic reaction. The defect sites were related to the initial coverage dependent region of the adsorption heats measured by gas-phase microcalorimetry

Carbon Nanotube Structures as Support for Ethanol Electro-Oxidation Catalysis

In the present study, the effect of support for ethanol electro-oxidation reaction was investigated on 20 percent Pt/C (E-Tek), 20 percent Pt/commercial CNT, and 20 percent Pt/home-made CNTs. Homemade CNTs were prepared by template synthesis method via chemical vapor deposition (CVD) method. Twenty percent Pt/commercial CNTs and 20 percent Pt/home-made CNTs were prepared by polyol method. The metal dispersions were determined from volumetric chemisorption measurements. These catalysts were tested as anode catalysts for the ethanol electro-oxidation reaction at room temperature by cyclic voltammetry. An optimization study was conducted to find out the optimum scan rate and optimum potential change for ethanol electro-oxidation reaction on 20 percent Pt/C (E-Tek) catalyst. Then, ethanol electro-oxidation measurements were performed on 20 percent Pt/C (E-Tek), 20 percent Pt/commercial CNTs, and 20 percent Pt/home-made CNTs catalysts in 0.5 M H(2)SO(4) + 0.5 M ethanol solution at 0.05 V/s scan rate and 1.2 V vs. NHE. Although the raw data indicated that the 20 percent Pt/commercial CNTs exhibited the worst performance, the performances of all of the catalysts were identical after normalizing the current values with respect to the exposed Pt site obtained from the volumetric hydrogen chemisorption measurements. These results indicate that only the metal dispersions improved ethanol electro-oxidation reaction and support did not have any effect on ethanol electro-oxidation reaction under the conditions used in this study

A double-functional carbon material as a supercapacitor electrode and hydrogen production: Cu-doped tea factory waste catalyst

In the present study, our main aim is to show that the first synthesized metal-doped tea factory waste (TFW) catalyst can be used in both hydrogen production and supercapacitor application. In this context, TFW catalyst doped with copper (Cu) (TFW-Cu) was synthesized for methanolysis of NaBH4 and supercapacitor measurement. In the presence of four different parameters (metal type, metal amount, carbonization temperature, and carbonization time), methanolysis experiments of NaBH4 were performed and the catalyst with the maximum hydrogen production rate (HPR) was determined. As a result, it was determined that the 30% Cu-doped TFW (TFW-30%Cu) catalyst had a maximum HPR at a carbonization temperature of 300 degrees C and a carbonization time of 60 min compared to other substances. As a result of the methanolysis experiments performed in the presence of TFW-30%Cu catalyst, the maximum HPR and activation energy were determined as 9475 mL (min.g)(-1) and 13.02 kJ mol(-1), respectively. In supercapacitor application, the capacitance of the electrodes in the presence of TFW-30%Cu was calculated as 7-19.9 F.(g)(-1). Thus, it is expected that the synthesized catalyst will make a promising contribution in both energy storage and energy production areas-especially for distributed generation systems operating in national networks

Glucose electrooxidation modelling studies on carbon nanotube supported Pd catalyst with response surface methodology and density functional theory

In this study, carbon nanotube supported Pd catalysts (Pd/CNT) are synthesized at different weight percentages by the sodium borohydride (NaBH4) reduction method to investigate catalytic performance of glucose electrooxidation reaction. 0.5% Pd/CNT, 3% Pd/CNT, and 7% Pd/CNT catalysts are characterized by using X-ray diffraction (XRD), electron microscopy with energy dispersive X-ray (SEM-EDX), and N2 adsorption-desorption measurements. The average particle size and surface area of 3% Pd/CNT catalyst are determined as 46.33 nm and 129.48 m2/g, respectively. Characterization results indicate that Pd/CNT catalysts are successfully prepared by NaBH4 reduction method. Cyclic voltammetry measurements are performed to investigate the effect of Pd loading for the glucose electrooxidation. CV results reveal that 3% Pd/CNT catalyst exhibits best glucose electrooxidation activity. Following this, experimental optimization is performed to obtain maximum glucose electrooxidation activity via response surface methodology (RSM). Estimated and experimental specific activities at optimum experimental conditions are assigned as 6.186 and 5.832 mA/cm2, respectively. To understand the glucose electrooxidation activity on the surface of Pd/CNT, surface modeling is also performed with density functional theory (DFT) method to investigate adsorption of glucose molecule on CNT supported Pd surface. The DFT results emphasize that the addition of Pd atom to the CNT structure significantly improves the catalytic performance in glucose electrooxidation